Teaching Away, Commercial Success, and Blocking Patent Doctrines All Under the CAFC Spotlight

“Given that obviousness determination involves a retrospective analysis with strong inherent potential for hindsight bias, parties must be mindful that the evidence of teaching away is not ignored or minimized.”

https://depositphotos.com/26568791/stock-photo-stage-spotlights.htmlIn The Chemours Company FC, LLC v. Daikin Industries, Ltd., Nos. 2020-1289, 2020-1290 (Fed. Cir. July 22, 2021) (“Chemours v. Daikin”), the Federal Circuit clarified three doctrines involved in the determination of obviousness: teaching away, commercial success, and blocking patents. While all three panel judges agreed that the Patent Trial and Appeal Board (“Board”) misapplied the commercial success and blocking patents doctrines, they disagreed as to the Board’s application of the teaching away doctrine. In contrast to the Board, the majority found evidence of teaching away in the prior art. But Judge Dyk, dissenting, found no such evidence and called the majority’s determination an impermissible expansion of the doctrine that now encompassed a reference’s mere preference for a particular alternative.


As previously reported, Chemours v. Daikin is an appeal arising from final written decisions in two inter partes reviews, each requested by Daikin. Chemours v. Daikin, Maj. Op. at 3. The reviews involved certain claims of U.S. Patent No. 7,122,609 (the “’609 patent”) and of U.S. Patent No. 8,076,4312. The specifications and the issues on appeal being identical for both patents, the opinion refers only to the ’609 patent. Id. at 3-4.

Chemours’s patents relate to a unique polymer that can be formed at high extrusion speeds while still producing a high-quality coating on communication cables. Id. at 4. Most relevant to the appeal, the claimed polymer has a specific melt flow rate range of about 30±3 g/10 min, which is a measure of high melt flow rate or the rate at which the melted polymer flows under pressure (i.e., during extrusion). Id. Higher melt flow rate allows faster coating of the polymer onto a wire. The Board found all challenged claims to be unpatentable as obvious in view of U.S. Patent No. 6,541,588 (“Kaulbach”) which discloses a polymer similar to the claimed polymer. Id.

Chemours appealed, arguing that the Board’s finding of obviousness was erroneous since Daikin had failed to show that a person of ordinary skill in the art would modify Kaulbach’s polymer to achieve the claimed invention. Id. at 6.


Teaching Away

The Manual of Patent Examining Procedure (M.P.E.P.) provides that a prima facie case of obviousness may be rebutted by showing that the art, in any material respect, teaches away from the claimed invention. M.P.E.P. §(III)(B). Relevant to teaching away, the Kaulbach polymer, like the claimed polymer, can be processed at higher speeds and at higher temperatures, is useful for coating wires and cables, and has a very narrow molecular weight distribution. Chemours v. Daikin, Maj. Op. at 6. Kaulbach notes discovering that prior beliefs that polymers in high-speed extrusion application needed broad molecular weight distributions were incorrect because a narrow molecular weight distribution performs better. Id. at 6-7. Kaulbach suggests that polymers used in high speed wire extrusion have melt flow rates of 15 g/10 min or greater. Id. at 7. Finally, in the Kaulbach example relied on by the Board, Sample A11, the melt flow rate is 24 g/10 min (the claimed rate is 30±3 g/10 min). Id.

The court pointed out that the Board (based on Kaulbach and other evidence relating to high coating speeds) was persuaded that the skilled artisan would have been motivated to increase the melt flow rate of Kaulbach’s Sample A11 to be within the recited range in order to achieve higher processing speeds, because the evidence taught that achieving such speeds might be possible by increasing a polymer’s melt flow rate. Id. at 7-8.

Note that while the Board acknowledged Kaulbach as stating that a narrow molecular weight distribution performs better at achieving high processing rates than polymers with broad molecular distributions, it nonetheless found that it was unclear why the skilled artisan would have been motivated to maintain such a narrow molecular weight distribution when seeking to achieve even higher coating speeds with Kaulbach’s Sample A11. Id. at 8. Further, in the Board’s view, portions of Kaulbach’s disclosure lacked specificity regarding what was deemed “narrow” and “broad,” and that it would have been obvious to “broaden” the molecular weight distribution of the claimed polymer. Id.

The court found the Board’s obviousness findings to be unsupported by substantial evidence since it appeared to have ignored the express disclosure in Kaulbach that teaches away from the claimed invention – the importance of maintaining a very narrow molecular-weight distribution when increasing melt flow rate – and to have relied on teachings from other references that were not concerned with the particular problems Kaulbach sought to solve. Id. at 9. It pointed to the Board’s statement that even though Kaulbach generically touts that high processing rates can be achieved despite a narrow molecular weight distribution, this purported discovery would not have prevented the skilled artisan, interested in achieving higher coating speeds with Sample A11, from considering other techniques – such as broadening the polymer’s molecular weight distribution beyond the narrow molecular weight distribution suggested, but not required or precisely defined, by Kaulbach. Id. at 8-9.

The majority contrasted the Board’s characterization with examples in Kaulbach of processing techniques typically used to increase melt flow rate, but which Kaulbach cautions should not be used due to the risk of obtaining a broader molecular weight distribution, namely: not using chain transfer agents during polymerization because they intrinsically broaden the molecular weight distribution; and not using high fluorination temperatures, because doing so can result in a broadening of the molecular weight distribution and negatively affect performance. Id. at 10. The majority concluded that these factors do not demonstrate that an ordinarily skilled artisan would have had a reason to attempt to get within the claimed range. Id.

Disagreeing with the majority, the dissent cited to numerous prior decisions of the court standing for the proposition that the fact that better alternatives exist in the prior art does not mean that an inferior combination is inapt for obviousness purposes. Chemours v. Daikin Dissenting Op. at 3. The judge noted that although Kaulbach’s invention is a narrow molecular weight distribution polymer, Kaulbach also acknowledges that the art taught that a broad molecular weight distribution was needed to achieve such high processing rates, and that prior art mixtures had a very broad molecular weight distribution, which, according to conventional wisdom, results in an improved extrudability. Id. at 3.

The dissent further noted that contrary to the majority’s assertion, modifying the molecular weight distribution of Kaulbach’s disclosure of 24 g/10 min melt flow rate to achieve 27 g/10 min melt flow rate (lower limit of the claimed range) would hardly destroy the basic objective of Kaulbach. Id. at 3-4. It pointed to the Board’s determination that Kaulbach does not precisely define what constitutes a narrow molecular weight distribution, only defining a “very narrow molecular-weight distribution” of “less than about 2” and “as low as 1.5.” Id. at 4. It noted that sample A11 has a measured distribution of 1.6, which is toward the lower end of this “very narrow” distribution range and as such, Sample A11’s molecular weight distribution could be increased by 0.4 (25%) while maintaining a “very narrow” molecular weight distribution under Kaulbach. Id.  The dissent found that there was no support for the theory that increasing the melt flow rate from 24 g/10 min (Kaulbach) to 27 g/10 min (the ’609 patent) (a 12.5% increase) would create more than a 0.4 increase (25%) in the molecular weight distribution and thus be contrary to Kaulbach’s supposed teaching to stay within the “very narrow” molecular weight distribution. Id. To the dissent, the majority’s contrary conclusion constituted nothing less than appellate factfinding. Id.

Commercial Success

Chemours made two arguments with regard to the Board’s treatment of the commercial success evidence. First, Chemours argued that the Board improperly rejected an extensive showing of commercial success by finding no nexus based on a limitation-by-limitation analysis, rather than taking the invention as a whole. Chemours v. Daikin, Maj. Op. at 12. Chemours contended that the novel combination of these properties drove the commercial success of FEP 9494 (a polymer covered by the claims). Id. The Board had found no nexus between the claimed invention and the alleged commercial success because Kaulbach disclosed all features except for the claimed melt flow rate, and other prior art of record disclosed melt flow rates of 50 g/10 min. Id.

The court clarified that contrary to the Board’s decision, the separate disclosure of individual limitations, where the invention is a unique combination of three interdependent properties, does not negate a nexus. Id. Concluding otherwise would mean that nexus could never exist where the claimed invention is a unique combination of known elements from the prior art. Id. at 12-13.

Chemours second argument was that the Board improperly required it to proffer market share data to show commercial success. Id. at 13. Chemours contended that the Federal Circuit has held that evidence of market share is not required to prove commercial success and that sales data alone should be enough for commercial success. Id.

The court agreed, pointing out that while the Board was entitled to weigh evidence and find, if appropriate, that Chemours’s gross sales data were insufficient to show commercial success without market share data, it erred in its analysis that gross sales figures, absent market share data, are inadequate to establish commercial success. Id.

Blocking Patent

On the blocking patents issue, Chemours argued that the Board erred when it found that the asserted patents were blocking patents that blocked others from entering the relevant market. Id at 14. The Board had determined that the existence of the ’609 patent covering the FEP 9494 product would have precluded others from freely entering the market, concluding therefrom that the evidence proffered to establish commercial success was weak. Id.

The court agreed with Chemours and found that the Board erred by misapplying the “blocking patents” doctrine to the challenged patents themselves. Id. The court explained that a blocking patent is one that is in place before the claimed invention because such a blocking patent may deter non-owners and non-licensees from investing the resources needed to make, develop, and market such a later blocked invention; however, the challenged patent, which covers the claimed invention at issue, cannot act as a blocking patent. Id.


The bulk of the Federal Circuit’s opinion relates to a discussion of teaching away, regarding which the Federal Circuit has previously said: “the prior art’s mere disclosure of more than one alternative does not constitute a teaching away from any of these alternatives because such disclosure does not criticize, discredit, or otherwise discourage the solution claimed….” In re Fulton, 391 F.3d 1195, 1201 (Fed. Cir. 2004). MPEP § 2145(X)(D)(1). Frequently, prior art technical description includes divergent teachings and may not appear to all to satisfy the teaching away standard to the same degree. This seems to be the case in Chemours v. Daikin, where, while the Board did not, the majority did find the prior art to discourage from increasing the melt flow rate since that would have led to broadening molecular weight distribution and altered the inventive concept. And, the dissent, while acknowledging that the prior art invention required a narrow molecular weight distribution polymer, viewed that polymer as a mere alternative.


Given that obviousness determination involves a retrospective analysis with strong inherent potential for hindsight bias, parties must be mindful that the evidence of teaching away is not ignored or minimized, especially where the prior art includes divergent teachings.

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Join the Discussion

5 comments so far.

  • [Avatar for Moderate Centrist Independent]
    Moderate Centrist Independent
    July 30, 2021 04:00 pm

    I keep copies of older editions in my office. A lot of good pro-applicant law can be found that has disappeared from the current mpep.

  • [Avatar for ipguy]
    July 30, 2021 01:37 pm


    You said it! There are so many portions of the MPEP which are horrendously warped interpretations of existing law. Furthermore, IMHO, older editions of the MPEP were far more balanced in their presentation of examples of what examiner could do and what they could not do.

  • [Avatar for Moderate Centrist Independent]
    Moderate Centrist Independent
    July 30, 2021 12:50 pm

    “The Manual of Patent Examining Procedure (M.P.E.P.) provides that a prima facie case of obviousness may be rebutted by showing that the art, in any material respect, teaches away from the claimed invention. M.P.E.P. §(III)(B).”

    I think most prosecutors are painfully aware just how flawed the MPEP can be.

  • [Avatar for step back]
    step back
    July 30, 2021 12:00 pm

    The dismissal of the teaching away argument is just another way of saying, “Even though the prior art taught to go one way (e.g. narrow molecular weight range), the ordinary artisan ‘could have’ tried all the other, less preferred ways (could be hundreds in this art) and ‘could have’ discovered the one variation that provides improvement for a different parameter (e.g. improved flow rate).”

    Could have. Should have. We’ve heard that hindsight cry many times before. It still works.